Power line networks are becoming increasingly common. Such networks are formed of devices (known as power line communication (PLC) devices) which communicate digital data over the in-building power lines and, as such, reduce the amount of wiring in a building.
There are a number of standards for power line networks, the most recent being the G.hn standard. Each one defines how the devices should operate and communicate with one another and with external networks. Since power lines extend beyond the reach of a single premises, thereby enabling neighboring networks to hear one another, it is imperative that the devices know to which network they belong. To this end, a “pairing” process was designed, in which a new PLC device “pairs” with another PLC device that is connected to the network, and receives an encryption key from that device. The current pairing mechanism requires that the encryption key be exchanged within a predefined time period (usually 2 minutes) from the time that the pairing is initiated.
The pairing process is usually initiated by depressing a switch on the PLC device. Usually, the user is instructed to press the switch for 2 seconds. A shorter or longer duration of the switch depression may not properly enable the pairing process.
Once the pairing process is initiated in the first PLC device, the user needs to repeat the process in the other devices on the network within a predefined time period—usually within 2 minutes. PLC devices that are installed in remote locations of the building may require more time to access and the allowed time period for completing the pairing process may not be sufficient.
Furthermore, once the pairing process is initialized, the PLC device will share its encryption key with any other device on the network if the other device has been initialized for pairing during the allowed time period. Thus, devices on neighboring networks that are within communication reach of the pairing device can retain the encryption key if they also happen to be initialized to pair at the same time.